Apparatus for controlling industrial processes



Feb. 27, 1934. E. B. FOOTE 1,949,199

APPARATUS FOR CONTROLLING INDUSTRIAL PROCESSES Filed Jan. 2, 1931INVENTOR TTORNEY 2 Patented Feb. 27, 1934 UNITED STATES PATENT OFFICEAPPARATUS FOR CONTROLLING INDUSTRIAL PROCESSES Edward B. Foote,Rochester, N. Y., assignor to Taylor Instrument Companies, Rochester,

6 Claims.

This invention relates t apparatus for carrying out an industrialprocess in accordance with a definite time schedule and more inparticular to apparatus includingTa cam having a composite surfacerepresenting a definite time schedule and a follower in contact with thecam for operating a plurality of translating devices.

In apparatus of this type a constant speed motor as the equivalent of atime piece is used to rotate the cam at a relativelyslow speed until thecycle of operation is concluded and a second motor is then set intomotion for rapidly continuing the rotation of the cam until the cam andthe follower are again in the same relative position as at the beginningof the cycle, to be ready for the next cycle.

Due to the nature of the cam surface and the translating devices it isdesirable and in most cases necessary that the cam and the follower bealways placed in exactly the same starting position. Due, on the otherhand, to the relatively high-speed motion of the cam on its return tothe starting position, which high-speed motion is desirable in ordertosave time, there is no certainty that the cam will come to rest in thedesired position.

The present invention has for its object to provide mechanism forcontrolling the relative move-- ment of the cam and the follower so asto make the'final position of the cam and the follower coincide with thestarting position.

The invention, briefly expressed, comprises means responsive to themovement of the-cam for holding the cam and the follower againstrelative movement when the cam and the follower have reached a definiterelative position.

In order to afford a full understanding of the invention and its mode ofoperation, reference is made to the drawing, wherein Fig. 1 is aschematic view of apparatus for controlling the operation of amachine-for preparing rubber stock for vulcanization, including theinvention; and

Fig. 2 is an enlarged sectional view showing the most essential part ofthe invention.

In the drawing 1 is a mixing chamber containing the rolls 2 which may bedriven by any suitable power plant not material to the invention. Abovethe mixing chamber is a feed hopper 3 together with a plunger-4 forforcing the material into contact with the rolls 2. At the bottom of themixing chamber is provided a slide gate 5and below' the gate aredisposed rolls 8 for discharging the material in the form ot'a sheet orwide ribbon for further treatment. The plunger 4 carfar side of themixing chamber when looking atthe drawing. The cylinder 4a is connectedat opposite ends to compressed air pipes '7 and 8 and the cylinder 5a.is similarly connected to compressed air pipes 9 and 10.

The rolls 2 are preferably continuously driven.

A- charge of rubber stock is first charged into the hopper through thedoor 3a, the slide gate 5 being initially in closed position. Theplunger 4 is then pressed down to continuously force the stock intoengagement with the roller until the stock has 7 been thoroughly brokenup and is ready for the mixing operation proper. The plunger 4 is thenretracted to-permit the charge of materials to be added. After thischarge has been entered; the plunger is again forced down as before andthe mixing operation is carried on' until it is completed. At any rate,the mixing operation isstopped when the temperature in the mixingchamber reaches a predetermined limit, when the slide gate 5 is openedand the plunger is retracted to its upper position. The stock is thendischarged. Whenthe temperature in the mixing chamber has dropped to acertain lower limit, the gate 5 is again closed, it being understoodthat this temperature limit is so chosen that, 9.0- cording toexperience, all the stock has left the mixing chamber. The apparatus isthen ready for a new cycle of operation.

The compressed air pipes '7, 8, 9 and 10 are controlled by valves 7a,8a, 9a and 10a, respectively, which in turn are operated by vdiaphragmtops 7b, 8b, 9b and 10b, respectively. Of these, diaphragm tops 9b and10b have each a single diaphragm actuated by compressed air admittedthrough pipes 90 and 100, respectively. Diaphragm tops 7b and 8b, 011'the other hand, have. each two diaphragms spaced from one another andseparably operable. In the top 1b the upper diaphragm is actuated by airconducted through pipe and the lower diaphragm is actuated by airflowing through pipe 7d. In top 8b, the upper diaphragm is actuated byair entering through pipe and the lower diaphragm is acted'u'pon by airadmitted through pipe 8d. As is well known, both diaphragms areconnected to the valve rod 7e and 80, respectively.

Compressed air-for the operation of the cylinders 4a and 5a is conductedto the valves la, 8a, 9a and 10a from a supply pipe 11. The valves arethree-way valves having exhaust ports if.

8f, 9} and 10 respectively. In one position of the valves, air flowsfrom the supply into the cylinders and in the other position airexhausts from cylinders into the atmosphere. It is understood that whenone end of a cylinder is under pressure, the other is connected to thecorresponding exhaust port.

The principal part of the operating mechanism is a control device 12containing a cam 13 having a. composite surface including an incline13a, the first concentric portion 132), a second incline 13c and asecond concentric portion 13d. The control device further includes aconstant speed motor 14 of usual construction functioning through asuitable gear train 90 to drive the cam; a separate motor includingpreferably a turbine wheel 15 and compressed air nozzles 16 and 17 fordriving said cam; a. follower 18 having at its upper end a finger 18afor engagement with the cam surface and a locking device to be morefully described and a plurality of valves actuated by arms 20 and 21 ofa. frame moved by the follower 18. The frame 22 is suspended on leafsprings 23, 24 and 25 for parallel motion and carries at one side knifeedge 26 or the like for engagement with a heel 27 at the lower pivotedend of the follower 18. Pivotal motion of the follower causes the frame22 to rise or fall whereby arms 20 and 21 press upon the valve stems ofvalves 30, 31, 32, 33 to open the valves or move away from the same toallow the valves to close, as the case may be. Compressed air isconducted to one side of the valves by means of a conduit 28.

From valve a connection 34 leads to the interior of a. housing 35 asshown in detail in Fig. 2 and to the nozzle 17. Within the housing 35 ismounted an expansible diaphragm 36 closed at one end and with its openend in air tight con-- nection with the wall of the housing. Within thediaphragm 36 is disposed a stud 37 one end of which is in contact withthe closed end of the diaphragm and the other end of which extendsthrough an aperture in a plate 38 which forms one wall of the housing. Aspring 39 bearing at one end against the inner side of the plate 38 andat its other end against the opposite end of stud 37 forces the latterto remain in contact with the closed end of the diaphragm and to move.

' with the latter. When air is admitted to interior and the free end ofthe stud 37 is of the housing 35, the diaphragm is compressed caused toproject outside the plate 38. The locking device 19, previously referredto, has at its upper end an aperture 40 in axial alignment with the stud37.

The outlet side of valve 31 is connected by means of a conduit 41 to thediaphragm top 42 of a valve 43 which controls a conduit 44 connectedwith the conduit 28 to a pressure reducer 45. The conduit 44 leads tothe pipes 70 and 80, to valve 46 of a temperature-sensitive device 47 tobe more fully described, and to a pneumatic switch 48. The outlet sideof valve 46 is connected by means of a conduit 49 to the diaphragm tops9b and 10b and to a pneumatic switch 50.

The outlet side of valve 32 is connected by means of conduit 51 to valve52 of the temperature-sensitive device 47, the outlet side of valve 52-being connected by means of conduit 56 to nozzle 16. Nozzle 17 isconnected to conduit 34-, as mentioned.

The outlet side of valve 33 is connected by means of conduit 53 to thepressure chambers of the lower diaphragms of diaphragm tops 7b and 8band a connection 53a leadsfrom conduit 53 to the upper end of apneumatic switch 54 and to the lower end of a pneumatic switch 55.

. Suitably disposed within the mixing chamber 1 is atemperature-sensitive bulb 57 connected by means of a capillary 57a totwo capsular diaphragms 58 and 59 which operate the valves 46 and 52,respectively.

The motor 14, in the particular instance; is a synchronous motor of wellknown type and is operated by an electric circuit 60. The pneumaticswitches 48, 50 and 54 interconnect the opposing sides of the circuitthrough lights 62, 63 and 64. Pneumatic switch 55 bridges the gap in oneside'of the circuit and therefore, when open, cuts out the motor 14. Aconnection 65, bridges switches 55 and 48, when the push button 66 isclosed, but the latter is normally open and closed only when it isdesired to start the cycle of operation, switches 55 and 48 beingautomatically operated to make or break the circuit.

In the following description, reference will be made to direct actingand reverse-acting valves and switches. The former term is generallyused to designate valves and switches which are moved to closingposition by application of a force (air in the present case) and movedto open position under the action of a spring when the force (air) iscut off. The latter term, on the other hand, denotes such valves andswitches which are normally closed and held in closed position by aspring and are moved to open position by the application of a force (airin this case).

Valves 7a and 9a and switches 50 and 54 are direct acting, while valves30, 31, 32, 33, 46, 52, 8a, 10a and 43 and switches 48 and 55 arereverse-acting.

The operation is as follows:

The cylinders 4a and 4b and all the valves and diaphragms and thenozzles 16 and 17 are operated by compressed air from the same source.By means of the reducer 45 the air pressure is reduced to a pressuresuitable for the operation of the diaphragms. While there is a greatdeal of latitude in this respect, I propose to use for the operation ofthe plunger 4 and the gate 5 a pressure of about 85 lbs. and for theoperation of the diaphragms, etc.,' a pressure of about 25 lbs.

The cycle of operation begins with the position of the cam 13 and thefollower 18 as indicated in Fig. l. The finger 18a is in a positionabout half way up the incline 13. The gate 5 is closed and the plungeris up. The operator fills the hopper 3 with the initial material. Whenthe hopper is filled, the operator pushes the button 66 to start themotor 14 and the cam begins to rotate in counter-clockwise direction. Assoon as the finger 18a has advanced slightly further up the incline1311, the valve .31 is allowed to close, thereby cutting the air fromthe diaphragm top 42 of valve 43, with the result that the latter closesand cuts off the air, in the first instance from the switch 48 allowingthe same to close. The switch 55 being also closed, the motor circuit isautomatically closed by the closing of switch 48 and the push button canbe released. At the same time, the air is cut off from the diaphragmtops of the valves 7a and 8a causing the former to open and the latterto close with the result that the plunger 4 is forceddown. With theclosing of the switch 48, the light 62 is energized indicating by itscolor, say white, that the operation is under way. The cam continues tomove until the finger reaches a point part way up the incline 130. Thecam,

which in practice is made in sections, as appears in the drawingparticularly Fig. 2, may be adjusted for any desired period of time forthe operation. At the present time, the minimum period is about one andone-half minutes and the maximum period about three minutes from thebeginning of the operation until the finger 18a reaches the incline 13c.

During this period, the air is also cut-ofi from valve 46, thesignificance of which will appear later on.

As soon as the finger 18a has reached a position slightly more thanhalf-way up the incline 130, the arm 20 has pressed against the stems ofvalves 32 and 33 to open them. From valve 1 33 air now flows to theswitches 54 and 55, the

former closing and energizing the light 64, which may be red forinstance, and the latter opening to stop the motor 14. As the same timeair flows through conduits 53 to the lower diaphragm of the tops 7b and31), causing valve 7a to close and valve 8a to open with the result thatthe plunger 4 is again raised.

From the valve 32 air flows through conduit 51 to the valve 52. However,this valve is closed and remains closed until the temperature in themixing chamber 1 reaches a certain temperature limit (about 150 F.) atwhich limit the diaphragm is suificiently expanded to open valve 52.

Now the operation is stopped until the operator has charged into themixing chamber the additional ingredients and again. pushes the button66. Now the motor starts again and the cam 13 continues its movement.The finger 18a moves up the remaining part of the incline 13c and thendrops back to the concentric portion 13d and continues on the latteruntil the temperature in the mixer has reached the critical limit. Whenthe finger 18a drops from the top of the incline 130 to the concentricportion 13d, valve 33 closes again, releasing the air from the lowerdiaphragms of tops 7b and 8b, whereby the plunger 4 is again lowered,and from the switches 54 and whereby the light 64 is extinguished andthe motor circuit automatically opened. Valve 32 remains open supplyingair to the valve 52.

As soon as the critical temperature in mixer is reached, the valve 52opens and furnishes air to the nozzle 16 causing a rapid movement of thecam in the same direction to quickly advance the cam to the initialposition.

When the finger 18a drops down from the concentric portion 13d to thefoot of the incline 13a, valves 32 and 33 are closed, but valves 30 and31 are opened. The closing of valve 32 shuts off the air from the nozzle16. Valve 31 supplies air to the diaphragm top 42 of valve 43 to openthe latter whereby the valves 7a and 8a are operated to raise theplunger and valves 9a and 10a are operated to open the slide gate 5 andthe switch 50 is closed to energize the light 63 which may be green forinstance, to show the completion of the cycle. At the same time valve 30supplies air to the nozzle 17 to continue the rotation of cam 13 and tothe housing 35. The air pressure within the housing 35 compresses thediaphragm 36 and causes the stud 3'7 to project through the opening inplate 38 into the opening 40 in the locking member 19. Opening 40 islarger than the projecting part of the stud 37 and is so disposed thatas the finger 18a rides up thein cline 13b, the edge of the opening 40(which appears to the left of the stud 37' in Fig. 1 and to the right ofthe stud in Fig. 2) comes into contact with the stud justas the finger18a reaches the starting position shown in Fig. 1, whereby the follower18 and the finger 18a are held against further movement. As the finger18a approaches the particular position mentioned, the valve 30 is closedand air is cut off from the nozzle 17, but it is'uncertain just howquickly the wheel 15 would stop and where the finger 1811 would come torest. Likewise valve 30 cuts off air from housing 35 and in due timediaphragm 36 retracts stud 37 from the opening 40 in the locking member19 on the follower. This last-named operation takes place after thefinger 18a. and the cam 13 have come to the desired position of rest.The purpose of the locking mechanism is to precisely fix the position of"the finger 18a for the starting of the next cycle.

The closing of valve 33 shuts off the air from the lower diaphragm ofvalve tops 7b and 8b at the same time the air is shut off from the upperdiaphragms, so that the valves 7a and 8a may reverse their positions. Atthe same time the air is shut on" from switches 54 and 55 to stop themotor 14 and extinguish light 64.

Air was admitted to valve tops Qband 10b,

through valve 46 which was open due to the expansion of capsulardiaphragm 58. However,

.when the temperature in the mixing chamber drops to a certain limit,say 120 F., the valve 46 closes again and shuts oif air from the valvetops 91) and 10b allowing the valves 9a and 10a to reverse theirrelative position to close the gate again.

As was previously mentioned, during the first part of the operation, 1.e. the break-down operation of the rubber, the air is cut ofi from thevalve 46 by the valve '43. Even if the temperature should reach orexceed the critical limit of 150 F. to open the valve 46', no air wouldfiow to the diaphragm tops of valves 9b and 10b to open the .gate 5.Similarly no air can flow to either'of the nozzles 16, 17 to prematurelyreturn the cam to the initial position, because no air is admitted tothe valve 52 until after the first part of the cycle is. completed andair can flow to the nozzle 17 only when the cam approaches the finalposition.

In the foregoing I have described the complete operation of a particularkind of apparatus to properly qualify the invention in a concretesetting. The mixing mill-and the control device, generally, do not forma part of the invention. The invention proper comprises the mechanismshown in Fig. 2, together with the valve 30 and their operative relationto other elements principally the earn, the follower, the wheel 15 andnozzle 17.

It is understood that the use of a pressure fiuid for operating the stud37 merely-represents one convenient means particularly suggested inconnection with the apparatus described.

While E have shown a pin as a movable abutment for interlockingengagement with the follower, the nature of the abutment, its motion andthe interlocking engagement may vary in various ways and theinterlocking action is by no means limited to the follower. My inventioncontemplates any construction whereby the cam and the follower are heldagainst relative movement when a definite relative position of the camand the follower is reached.

The present application is related to the following copendingapplications: E. B. Foote, Ser. No. 464,099, filed June 26, 1930, nowPatent No. 1,921,740, issued Aug. 8, 1933; E. B. Foote et al., Ser. No.464,100, filed June 26, 1936, now Patent No. 1,921,741, issued Aug. 8,1933.

I claim:

1. In apparatus of the character described, the combination with a camhaving a composite surface representing a definite time schedule and afollower positioned to contact with the cam surface, of means fordriving the cam at a relatively slow speed from an initial definiterelative position of the cam and the follower through part of onerevolution, means for driving the cam at a relatively high speed throughthe remaining part of one revolution, means for de-energizing the highspeed driving means when the cam substantially reaches its initial'position and means operative to hold the cam and the follower againstrelative movement when said initial position is reached.

2. Apparatus according to claim 1, including means responsive to themovement of the cam for energizing the said cam and follower holdingmeans when the cam approaches said definite position and forde-energizing the same when the said definite position is reached.

3. In apparatus of the character described, the

combination with a cam, a follower contacting with the cam, means forrotating the cam and means for holding the cam and the follower againstrelative movement in a definite relative position, including aportion.of the follower having a perforation, a pin movable at rightangles .to the plane of motion of the follower into and out of saidperforation and means responsive to the movement of the cam foractuating the pin.

4. In apparatus of the character described, a regulating mechanism forterminating the operation of a device in one stage of its cycle of operation in accordance with the expiration of a predetermined timeinterval and in another stage of its cycle in accordance withtemperature, said regulating mechanism including timing means to measuresaid predetermined intervalof time, and means operative responsive to apredetermined temperature to accelerate the speed of operation of saidtiming means.

5. In apparatus of the character described, a regulating mechanism forterminating the operation of a device in one stage of its cycle ofoperation in accordance with the expiration of a predetermined timeinterval and in another stage of its cycle in accordance withtemperature, said regulating mechanism including time means to measuresaid predetermined interval of timing, and means operative responsive toa predetermined temperature to control the speed of operation of saidtiming means.

6. In apparatus of the character described. the combination with a camhaving a composite surface representing a definite time schedule, amotor for driving the cam, a follower positioned to contact with the camsurface and translating mechanism for cooperation with the follower, ofmeans operatively connected with the follower for de-energizing themotor when the cam and the follower approach a definite positionrelatively to one another, and means operatively connected with thefollower for holding the cam.and the follower against relative movementwhen said definite relative position is reached, said means for holdingthe cam and the follower'against relative movement including meansresponsive to the movement of the cam for making the holding meanseffective when the cam approaches said definite position and for makingit ineffective when said position is reached.

EDWARD B. FOOTE.

